New Delhi (CNN) -- When 33-year-old Ashoo Mongia visits the supermarket it's rarely for stocking up his fridge for the week. As head of a cow protection enforcement team, he regularly scours Delhi grocery stores and outdoor markets for food products containing cow beef.

For the last 15 years, Mongia and his team of 120 Delhi-based volunteers have thrown themselves in a battle that pits India's billon-dollar meat industry and growing underground beef trade against Hindu traditionalists keen on preserving the holy status of cows.